Automatic telephone system



Nov. 22, 1927.

B. D. WILLIS AUTOMATIC TELEPHONE SYSTEM 2 eats-Sheet l Original FiledJan. 28. 1920 Nov. 22, 1927. 1,650,409

B. D. WILLIS AUTOL iATIC TELEPHONE SYSTEM Original Filed Jan. 28, 1920 2Sheets-Sheet 2 Ififin'ff Bernard D. M11115.

Patented Nov. 22, 1927.

UNITED STATES PATENT OFFICE.

BERNARD D. WILLIS, OF OAK PARK, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNHENTS, TO AUTOMATIC ELECTRIC Ill'C, OF CHICAGO, ILLINOIS, A CORPORATION OFDELA- WARE.

Application filed January as, 1920, Serial No. 354,814. Renewed m 21,1925.

My invention relates in general to automatic telephone systems, but moreparticularly to measured service automatic telephone systems; and hasfor its principal object the provision of means for assessing charges inlarge systems comprising a number of more or less widely separatedexchanges, the charge assessing means belng capable of automaticoperatlon in any g ven case to assess a variable charge, dependlng,first, on the exchange with which the connection is established, andsecond, on the duration of the conversation.

A measured service system arranged to antomatically charge variableamounts for connections to different exchanges is commonly known as azone metering system. I do not claim to be the" first inventor of such asystem, and refer to the U. S. patent to Powell, #1,303,958, which showsa representative system of this class. I have, however, devised certainimprovements; and provide in a systemv of this general character, notonly means for assessing a variable charge, which I call the initialcharge. but also means for assessing either a fixed unit charge or avariable charge at variable time intervals during the conversation, thusproviding a system more adaptable to the various conditions confrontingoperating telephone companies.

The foregoing and other useful objects are accomplished by means whichwill be fully described and explained hereinafter, reference being hadto the accompanying drawings, comprising Figs. 1 and 2, which arecircuit diagrams of so much of the exchange equipmentas is necessary foran understanding of the invention.

Referring to the drawings, I have shown therein only a portion of theapparatus required to complete a connection between a calling and acalled subscriber: but in view of the well known character of theapparatus, and of the fact that telephone systems of this character arenow wellunderstood, it is believed that sufficient has been shown toenable the invention to be readily understood.

In Fig. 1, the substation indicated by reference character A, is anordinary automatic substation which comprises the usual talkingequipment and ringer, and also a calling device S, through the medium ofwhich the subscriber controls the central ofiice switches.

The line conductors 11 and 12 extend to the exchange where theyterminate in the rotary line switch 0, which may be briefly described asa line switch whose wipers have a rotary movement in a forward directiononly, and which have no normal position. That is, when the switch isreleased the wipers do not return to normal but remain on the set ofcontacts last used. A plurality of .these individual ,line switches maybe given access to a grbup of trunk lines extending to first selectorswitches, and one of the trunk lines to which the line switch C hasaccess is shown in the drawing as extending to the first selector D. Theselector D is a vertical and rotary switch of familiar construction, andtogether with a plurality of similar selectors, has access to aplurality of groups of trunk lines.

a s before mentioned, the system which is being described herein,contemplates a plurality of exchanges and the different groups of trunklines to which the first selectors have access will ordinarily extend todifferent exchanges, although one or more groups may of course go 'tothe same exchange, while ordinarily at least one group will be reservedfor local trafiic. In the drawing I have shown two sets of contacts inthe first and second levels of the selector D, but it is understood thatthe selectors will have ten levels corresponding to ten different groupsof trunk lines. One of the trunk lines terminating in the first level isthe trunk line comprising conductors 76, 77 and 78 which extends to therepeater B (Fig. 2) and then continues by way of conductors 200 and 201,to a distant exchange, where the conductors 200 and 201 terminate in theline, relay of a second selector switch.

The repeater R comprises the group of relays shown in the upper half ofFig. 2, and has the usual functions of a repeater in a two wireautomatictelephone system. As-'; sociated with each repeater there is provided anauxiliary switch, which in the case of the repeater R is indicated bythe reference character P. The auxiliary switch P is a rotary step bystep switch of simple construction, having two semi-circular rows ofbank contacts which are adapted to be engaged by the wipers 153 and 154,respectively. The shaft carrying the said wipers is given a step by steprotary movement by means of the rotary magnet 150. Backward movement ofthe shaft is prevented by a pawl in the usual manner, and the release ofthe switch is brought about by the withdrawal of the said pawl undercontrol of the release magnet 152. The function of the auxiliary switchP is to actuatethc meter of each calling substation which establishes aconnection by way of the repeater R in accordance with the proper chargefor the connection.

Having described in a general way the apparatus shown herein, I will nowdescribe the operation briefly during the establishment of theconnection, with special reference to the operation of the auxiliaryswitch P in controlling the meter of the calling subscriber, after whicha more general explanation will be given of the difierent methods ofconnecting the bank contacts of the auxiliary switches associated withthe different trunk groups in order to take care of difi'erenttollcharges. It will be assumed that the subscriber at substation A desiresto connect with a subscriber in the exchange to which the trunk linecomprising conductors 200 and 201 extends. When the receiver is removedat substation A, a circuit is completed over the line conductors 11 and12 for the line relay 14 of the line switch C. Upon energizing, the linerelay 14 completes av circuit extending through the switching relay 13and the stepping magnet 21 in series to battery. This circuit iscompleted at armature 20 of the line relay, and at armature 19 the testwiper 32 is connected to the above circuit at a point midway between theswitching relay and said stepping magnet. The operation now depends uponwhether the test contact with which the test wiper 32 is in engagementis busy or is not busy. If this test contact is busy it will have aground potential upon it, the switching relay 13 will be shortcircuited, and the stepping magnet 21, which interrupts its own circuit,will be operated in the manner of a buzzer to advance the switch wipers30 to 33, inclusive, step by step in search of an idle trunk line. Thisoperation will continue as long as the test wiper 32 continues to engagegrounded or busy testcontacts. However, we may assume that in thepresent case. when the call is initiated, the selector D is idle, and atest contact 36 therefore is not grounded. In these circumstances, whenthe line relay 14 is energized the switching relay 13 is energizedimmediately afterwards, with the result that the line conductors 11 and12 are disconnected from the line relay 14 and from ground,respectively, and are extended by way of armatures 15 and 18 and theirworking contacts, line wipers 30 and 33, trunk conductors 38 and 40, andarmatures 60 and 63 and than resting contacts to the upper and lower-Windings respectively, of the .line relay 50 of the selector D. I

Upon the extension of the callingvline as above described, the linerelay 50 will be energized over the line circuit and will close acircuit for the slow acting release relay 51. Upon energizing, relay 51prepares the selector D for vertical operation in the usual g/manner,and also completes a holding circuit extending back to the line switch Cover the following path: ground at G working contact of armature 64 andthe said armature, conductor 39, test contact 36, test wiper 32,armature 17 and its working contact, winding of switching relay 13, andthe winding of the stepping magnet 21' to battery. It is understood thatthe above circuit is established before the slow acting relay 14 has hadtime to deenergize. It will be observed that there is a branch circuit'extending from the grounded conductor 39 by way of the resistance 43,and the winding of relay 42 to battery. Relay 42 is a marginal relay andis not energized at the present time.

The calling subscriber may now operate his calling device in accordancewith the first digit of the desired number. A series of interruptions isthereby produced in the circuit of line relay 50, causing acorresponding se-' ries of deenergizations of the said relay, which ateach deenergization sends a current impulse through the slow actingrelay 52 and the vertical magnet 56 to battery. By the operation of thevertical magnet 56 the switch shaft is raised step by step until thewipers to 72, inclusive, stand opposite the bank level in which areterminated the trunk lines leading to the desired exchange. In thepresent case. the wipers will be raised opposite the level containingbankcontacts 73 to 75, inclusive. The slow acting relay 52 is energizedin serieswith the vertical magnet, retaining its armature attractedthroughout the vertical movement oft the switch, and upon the closure ofoff normal contact springs-58, completes a circuit for the steppingrelay 53. Upon energizing, relay 53 establishes a locking circuit foritself at its upper armature, and at the lower armature prepares acircuit for the rotary magnet 54. At the end of the vertical movement ofthe switch the slow acting relay 52 is deenergized and closes thecircuit of the rotary magnet, which is thereupon energized to ro tatethe switch wipers into engagement with the first set of bank contacts inthe level opposite which they were raised. The rotary, magnet alsobreaks the locking circuit of the stepping relay 53, which accordinglyis deenergized to break the circuit of the rotary magnet, whichthereupon deenergizes also, and again closes its interrupter contact.The operation now depends upon whether the test contact with which thetest wiper 71 is in engagement is busy or is not busy. If this testcontact is busy it will have a ground potential upon it, and thestepping relay 53 will again be energized over a circuit which extendsfrom the grounded test contact by way of the test wiper 71, armature 61and its resting contact. interrupter contact of the rotary magnet 51,off normal springs 58. and the winding of the stepping relay 53 tobattery. The stepping relay will therefore again close the circuit ofthe rotary magnet. which will operate to advance the switch wipers intoengagement with the next set of bank contacts. This operation in whichthe stepping relay and the rotary magnet 54 are alternately energizedand deenergized takes place very rapidly, and will continue as long-asthe test wiper 71 continues to engage busy or grounded test contacts. Inthe present case it will be assumed that the trunk line shown in thedrawing is the first idle trunk line, and when, therefore. the testwiper 71 arrives at test contact 74 and the rotary magnet 54 isdeenergized, the stepping relay 53 will not again be energized; but theswitching relay 55, which heretofore has been short circuited, will beenergized by current flow over the following path: grounded conductor39, winding of switching relay 55, interrupter contact of the magnet 54.off normal springs 58, and the winding of the stepping relay 53 tobattery. Owing to the high resistance of the switching relay thestepping relay 53 is not energized by current flow in the above circuit.Upon energizing, relay 55 disconnects the trunk conductors 38 and 40from the windings of the line relay 50 and extends them by way ofarmatures and 63 and their working contacts. line wipers and 72, bankcontacts 73 and 75, conductors 76 and 78, and normally closed contactsof reversmg relay 100,'to the upper and lower windings, respectively, ofthe double wound line relay 101 of the repeater R The line relay 101 isaccordingly energized over the line circuit and upon attracting itsarmature 110 completes a circuit for the slow acting release relay 102.Upon energizing. relay 102 closes a circuit through the polarizingwinding of the electro-polarized relay 104 at its armature 113, and atits armature 114 completes a holding circuit extending back to theselector D over the following path: ground at G normally closed contactsprings controlled by-armature 123, working contact of armature 114' andthe said ari'i'iature. conductor 77. test contact 74. test wiper 71, andarmature 01. and its working contact to'the conductor 30. where it joinsthe previously described holding circuit extending back to the lineswitch C. The circuit just described serves to maintain relays 55 and 13energized throughout hand winding of impedance coil 10?, and armature111 of the now energized line relay 101 and its working contact to thetrunlcconduct-0r 201. By the closure of the bridge just described acircuit is completed for the line relay of the second selector in thedistant exchange (not shown) in the usual manner. and the said linerelay and its associated slow acting release relay are accordinglyenergized and the distant selector is prepared for operation.

The calling subscriber may now operate his calling device in accordancewith the next digit in the desired number, thereby causing a series ofdeenergizations of the line relay 101 of the repeater R, which at eachdeenergization opens the bridge across the trunk conductors 200 and 201and thereby interrupts the circuit of the line relay of the distantselector switch. The said selector is accordingly operated in the wellknown manner to raise its wipers in accordance with the digit called,after which the said wipers are rotated and connection is establishedwith an idle trunk line which may extend either to another selectorswitch or to a connector switch. depending upon the size of theexchange. At the repeater It, while the line relay 101 is deenergizingintermittently to repeat impulses to the second selector switch in thedistant exchange, it sends an impulse at each deenergization to slowacting relay 108. This relay is energized upon the first impulse andmaintained energized throughout the series of impulses to complete thebridge across trunk eon-- ductor 200 and 201 over a non-inductive pathwhich may be traced from trunk conductor 200 by way of armature 115 andits working contact. armature 11R and its working contact, and armature111 and its working contact to the trunk conductor 201. This operation,by removing the windings of relay 104 and impedance coil 107 from thecircuit, produces a better control circuit for operating the series ofswitches in the distant exchange.

The calling subscriber may now call the remaining digits in the desirednumber, with the result that additional series of interruptions areproduced in the circuit of the line relay 101. which operates as beforeto repeat the interruptions, and thereby brings about the operation ofthe remaining switch or switches in the distant exchange which arerequired to complete the comu-iction with the called subscribers line.The bell at the ly, and when the called subscriber removes his receiverresponsive thereto, the ringing equipment is automatically cut off, andthe called station is supplied with talking battery through the windingsof the back bridge relay of the connector in the usual manner. As iscustomary, this back bridge relay is provided with contact springs whichreverse the connections'of the incoming line conductors, therebyreversing the direction of current flow over conductors 200 and 201, andthrough the lower winding of the electro-polarized relay 104 at therepeater B. As a result, the relay 104, which heretofore has remainedinoperative, is operated, and at its armature 118 closes circuitsthrough relays 100 and 105. Relay 100 is a reversing relay whichreverses the direction of current flow in the incoming trunk conductors76 and 78, for no useful purpose however, in connection with theapparatus shown; but inasmuch as it is a standard operation and is ofutility under certain circumstances which it will not be necessary tomention the circuits have been shown in this manner. Relay 100 alsoconnects an additional pair of condensers, and includes the left handwinding of the impedance coil 107 in series with the right hand winding,with the object of increasing theefliciency of the talking circuit. Thecomplete connection has now been established and the subscribers mayconverse as desired.

The manner in which the meter M associated with the calling subscribersline is operated will now be considered. When the relay 105 is energizedby the closure of its circuit at armature 118 of relay 104, aspreviously mentioned, the said relay establishes a locking circuit foritself and its armature 120, and at its armature 121 closes a circuitover conductors 160 and 161 for the stepping magnet 150 of the auxiliaryswitch as will appear hereinafter, other time inter vals may be used toadvantage in.certain cases. To continue with the explanation, when thecircuit of the stepping magnet 150 is closed by relay 105 the saidstepping magnet will be operated every three seconds to rotate thewipers 153 and 154 step by step over the bank contacts associatedtherewith. When wiper 154 arrives at bank contact 164, and the steppingmagnet 150 deenergizes, a circuit is completed for the relay 106 of therepeater R'as follows: ground at G, contact springs controlled by thestepping magnet 150, wiper 154, bank contact 164, conductor 165, restingcontact of armature 157 and the said armature, conductor 159, and thewinding of relay 106 to battery. Upon attracting its armature 123, relay106 alters the previously described holding rircuit extending back overconductor 77 to selector D and line switch G to the extent that the saidholding circuit is completed from ground G by way of battery B andresistance X instead of from ground G. By this operation the battery Bis connected in series with the exchange battery and causes an increasedflow of currentthrough the marginal relay 42. As previously stated thisrelay 42 is marginally adjusted and has remained inoperative up to thepresent, but is now sufliciently energized to enable it to attract itsarmature 44, thereby closing a circuit which extends from ground by wayof the said armature 44, bank contact 35, wiper 31, working contact ofarmature 16 and the said armature, and the, winding of the operatingmagnet of meter M to battery. The meter is therefore operated toregister one unit charge against the calling subscriber. Relays 106 and42 are deenergized and the circuit of the meter magnet is broken whenthe wiper 154 is stepped off from bank contact 164 and onto the nextbank contact, but when the wiper 154 arrives at bank contact 166 thecircuit of relay 106 is again closed by way of conductor 168 andarmature 155 and its resting contact, so that the meter M Will beoperated to register another unit charge. The same thing occurs whenwiper 154 arrives at bank contact 167, and it will be seen thereforethat within 15 seconds the meter of the calling subscriber will beoperated three times to register three unit charges. Nothing furtheroccurs until the wiper 154 arrives at contact 170, when a circuit willbe closed by way of the wiper 154, bank contact 17 0, conductor 169,normally closed contact springs controlled by armature 156. and thewinding of relay 151 to battery. Upon energizing, relay 151 establishesa locking circuit for itself at armature 156 and at armature 155disconnects conductor 168 from conductor 165. After the expiration ofone minute, wiper 154 will arrive at contact 172, which is connectedwith bank contact 164, and the circuit of relay 106 will again be closedand the meter M will again be operated to register another unit charge.This operation is repeated when the wiper 154 arrives at bank contact173, which will occur upon the expiration of another minute. When thewiper 154 arrives atthe last contact in its bank, which it will do oneminute later, wiper 153 will engage bank contact 174, thereby closing acircuit by way of 'ill the said wiper 153, which is grounded, bankcontact 174, conductor 175, and the Winding of the release magnet 152 tobattery. Upon energizing, the release magnet 152 opens the connectionbetween conductors 165 and 159 at its armature 157, and also releasesthe switch in any well known manner, Whereupon the wipers 153 and 15 areat once restored to normal position. The release magnet 152 ismaintained energized by the circuit through the bank contacts engaged bythe wiper 153 until the wipers are restored to normal. The release ofthe switch P is completed within the three second interval, and when thestepping magnet 150 receives another impulse, the wipers are againstarted on their rotation over their associated bank contacts, and themeter M will be operated once each minute as long as the subscriberscontinue to converse, the switch P being released as many times as isnecessary. It will be noticed that during the second rotation of theswitch P, and all subsequent rotations, the meter will not be operatedwhen the wiper 154 passes bank contacts 166 and 167, due to the factthat the relay 151 was energized and locked up on the first rotation ofthe switch.

When the conversation is finished both subscribers will hang up theirreceivers. When the receiver is replaced at substation A, all theswitches involved in the connection are released and restored to normal,the release being initiated by the denergization of the line relay 101of the repeater R. Upon denergizing, relay 101 opens the bridge acrossthe trunk conductors 200 and 201 which causes the switches in thedistant exchange to release in the usual manner. The slow acting releaserelay 102 is also deenergized following the deenergization of the linerelay 101, and breaks the holding circuit extending back over conductor77 to the selector D and line switch C. As a result, relays 55 and 13are deenergized and the said switches are restored to normal in theusual and well understood manner. The auxiliary switch P, which isassociated with the repeater E is also released upon the deenergizationof the release relay 102 by the closure of the following circuit:grounded armature 110 and its resting contact, armature 112 and itsresting contact, working contact of armature 122 and the said armature,conductor 162, and the winding of the release magnet .152 to battery.This circuit is broken by the deenergization of relay- 105 an instantafter it is completed, but the complete release of the auxiliary switchis insured by the circuit over wiper 153 which was previously'described,The apparatus has now been all completely restored to normal positionand is ready for use in another connection.

I will now describe briefly how the auxilcorrespond to a differentexchange, one of which may be the local exchange, or the exchange towhich the substation A is connected, while the other exchanges may besituated at variable distances from the local exchange. In a case ofthis kind it is desirable to charge different amounts for connections tothe different exchanges in order to equitably distribute the cost of thetelephone service among the difi'erent subscribers; and from what hasbeen said already it will be understood that the charge to be assessedagainst the calling subscriber in any given case will be determined bythe exchange in which the called subscriber is located. This in turn isdetermined by the level selected at the first selectors, and it followstherefore that by suitably wiring the banks of the auxiliary switchesassociated with the different groups of repeaters, the properarrangement for varying the toll charges will be obtained.

[I have shown below a table which gives the toll charge per connectionfor each selector level, and which shows to some extent thepossibilities of the system. The table is based on a charge of 5 centsfor each actuation of a subscribers meter.

B-cent unit elapsed time charge time interval, in minutes.

Initial charge.

Trunk group.

In the above table the sixth level, which carries the least charge ofall, is assumed to be the level which is assigned to the local trunks.One of the trunks in the first level. together with the repeater R andassociated auxiliary switch P areshown in the drawing, and the manner inwhich the initial charge of 15 cents and the elapsed time charge of 5cents per minute are assessed against a calling' subscriber have alreadybeen explained. According to the table the exchange which is accessibleby way of the second level carries an initial charge of 10 cents and anelapsed time charge of 5 cents for every three minutes. In order toobtain this char e the auxiliary switches which are associa with therepeaters for the second level are wired as follows: Conductor 168 isconnected to bank contact 166 only, while conductor 165 is connected tobank contact 164 only. A consideration of the operation of the auxiliaryswitch will show that with this wiring arrangement, the meter of thecalling subscriber will be operated twice initially, once more after theexpiration of three minutes, and every three minutes thereafter. Theexchange which is accessible by way of the third level of the firstselectors carries the same initial charge, but has an elapsed timecharge of 5 cents for every 1% minutes. The

connections therefore are the same as just described, except thatconductor 165 is connected not only to bank contact 164:, but also tobank contact 176. The next case shows the 15 cent initial charge, whichis of course obtained by connecting conductor 168 to contacts 166 and167 as shown in the drawing.

. The exchange which is accessible by way of the fifth selector levelcarries a 15 cent initial charge and a 10 cent charge every threeminutes. In order to obtain this double elapsed time charge conductor165 is preferably connected to bank contacts 164 and 166, whileconductor 168 is connected only to bank contact 167. With thisarrangement of the wiring the meter of the calling subscriber Will beoperated three times initially and twice every three minutes thereafter.The wiring for the auxiliary switchesassociated with the other levels mabe calculated very easily from what has een said, and need not beexplained in detail. It is to be understood that auxiliary switcheshaving either larger or smaller contact banks may be used, and also thetime mechanism T may be arranged to give a different timed impulse, thatis, the interval between impulses transmitted by the time mechanism maybe altered as for example, to-5 seconds or any other desired value. Inthis manner the system shown may be-adapted to any telephone system inorder to take care of the different toll charges which are considered tobe most desirable under the circumstances, although the arra ement shownwill probably be found siifliclently flexible under ordinary conditions.i

It will be seen from the foregoing that I have devised a measuredservice system in which a variable initial charge is assessed against acalling subscriber, depending on the exchange to which he has extended aconnection; and in which an elapsed time charge is assessed against acalling subscriber which also is variable, either as to amount of theunit charge or as to the rate at which the unit charge is assessed, all

depending as in the case of the initial charge on the exchange to whichthe connection has been extended.

Having described my invention, what I consider to be new and desire tohave protected by Letters Patent will be pointed out in the appendedclaims.

What I claim is:

1. In a telephone system, a pluralit of exchan 'es, means for connectinga ca ling subscri er in one of said exchanges with called subscribers inthe other exchanges, 'toll assessing mechanism operated automatically inthe course of such connections to assess periodic elapsed time chargesagainst the calling subscriber, and means for varying the amount of thesaid periodic charges assessed durin the different connections and alsothe time intervals intervening between the assessing of successivecharges, both the amount of the charge and the time interval beingvaried in accordance with the exchange in w ich the called subscriber islocated.

2. In a telephone system, a pluralit of exchanges, means for connectinga ca ling subscriber in one of said exchanges with called subscribers inthe other exchanges, toll assessing mechanism operated automatically inthe course of such connections to assess against the calling subscriberan initial charge at the beginning of each conversation and periodicelapsed time charges during each conversation, and means for varying theamount of the initial charges and also the time intervals interveningbetween the assessing of successive elapsed time charges, both variablesbeing adjusted in accordance with the exchanges in which the calledsubscribers are located.

3. In a telephone system, a plurality of exchanges, means for connectinga calling subscriber in one of said exchanges with called subscribers inthe other exchanges,

toll assessing mechanism operated automati-' cally in the course of suchconnections to assess against the calling subscriber an initial chargeat the beginning of each conversation andperiodie elapsed time chargesduring each conversation, and means for varying the amount of theinitial charge, the amount of the periodic elapsed time charge, and thelength of the elapsed time charge time interval, all of said variablesbeing adjusted in accordance with the exchanges in which the calledsubscribers are located. I

4. In a telephone system, calling and called lines, means for extendingconnec-. tions from the calling line to said called lines, a meter forthe calling line, a meter controlling device operated when connection isextended to one of said called lines for operating the meter apredetermined num- 'ior causing said device to operate said meter acertain reduced number of times for each interval or time the connectionis held.

5. In a telephone" system, subscribers lines, a meter for each line,trunk lines for extending connections between said lines, and anauxiliary meter controlling switch for one of said trunk lines, saidswitch having a series of contacts so connected as to operate the meterof a calling line a plurality of times when the wiper of the switchtraverses said contacts the first time, and a lesser number of timeseach time said wiper traverses said contacts thereafter in the sameconnection. I

6. In a telephone system, subscribers lines, a meter for each line,trunk lines, means for establishing connections between any of saidlines over said trunk lines, and an auxiliary switch associated with oneof said trunk lines for controlling the operation of a callingsubscribers meter, saidv switch operated during conversation over itsassociated trunk line to first operate the meter a plurality of times toassess a line charge, and thereafter to operate the meter a reducednumber of times for each interval of elapsed time.

7. In a telephone system, calling and called lines, a meter for thecalling line, trunk lines, means for establishing connection betweensaid lines over said trunk lines, a rotary switch associated with atrunk line for controlling the meter of the calling line when the trunkline is used, certain of the contacts of said switch being connected toground and said switch having a wiper for engaging said groundedcontacts to send a plurality of impulses to the meter during the firstrotation of the switch, and means for disconnecting the ground fromcertain of said contacts after the first rotation to cause the meter tobe operated a reduced number of times for succeeding rotations of saidswitch.

8. In a telephone system, a plurality of exchanges, means for extendingconnections from a calling subscriber in one exchange to calledsubscribers in the other exchanges, a toll assessing device operatedwhen a connection is extended to a called subscriber in a certainexchange for assessing aninitial trunk charge against the callingsubscriber and also an elapsed time charge at predetermined intervalsduring the conversation, a different toll assessing device which isoperated when the called subscriber is located in each of the otherexchanges, and different circuit connections in each toll assessingdevice, whereby the initial charge, the elapsed time charge, or thepredetermined time. in-

,terval may be varied in accordance with the exchange in which thecalled subscriber is located.

.9. A meter controlling device comprising a bank of contacts, a wiper, amotor magnet for driving said wiper over said contacts repeatedly, amain meter control wire connected to one of said contacts, a branch wireconnected to another of said contacts, and

means for automatically disconnecting said branch wire from the mainwire before said wiper is driven over the said contacts the second time.v c

10. A meter controlling device comprising a continuously driven switch,a meter control wire, means operated at a certain stage in the operationof said switch for transmitting a series of impulses over said wire,said means being eifective the first time the switch passes through suchstage, and a switching device for causing said means to transmit adifferent series of impulses over said wire the next time the switchpasses through such stage.

11. In a meter controlling device, a continuously revolving operatingmember having active and passive positions through which it passesalternately, a meter control circuit closed a plurality of times by saidmember the first time it passes through its active position, and aswitching device for causing said member to close said circuit adifferent number of times the next time it passes through its activeposition.

12. In a telephone system, a meter, common mechanism for causing saidmeter to record a call charge and additional duration charge, therespective charges being constituted of one or more impulses to themeter, the impulses emanating from a source apart from the commonoperating mechanism. and

vmeans for preventing the application of impulses constituting the timecharge being applied untilafter the impulses constituting the initialcharge have been applied.

13. In a. telephone system, a toll meter including common operatingmechanism for recording a call charge and an additional duration chargea meter control conductor over which only impulses effective to controlthe meter in accordance with the initial charge are transmitted andanother meter control. conductor over which impulses are transmittedwhich control the meter in accordance with both the initial and durationcharge.

14. In a telephone system, a toll meter including common operatingmechanism for recording a call charge and an additional duration charge,the respective charges being constituted of one or more impulsesoperative to the meter, the said charge impulses emanating fromdifferent sources apart from said operating mechanism, an oscillatorywiper and means whereby the said impulses constituting the call chargeare picked up by said wiper during one oscillution and whereby theimpulses constituting a duration charge are picked up by a subsequentoscillation of said wiper.

15. In a telephone system, a toll meter including common operatingmechanism for recording a call charge and an 'yadd1t1onal durationcharge, the respective charges being constituted of one or more impulsesoperative to the meter, the said charge impulses emanating fromdifferent sources apart from the said operating mechanism,

and means including a wiper and an associ- Signed by me at Chicago,Illinois, this- 22d day of January, 1920.

-- BERNARD D. WILLIS.

